64141-11-3Relevant articles and documents
Evaluation of Cyclic Amides as Activating Groups in N-C Bond Cross-Coupling: Discovery of N-Acyl-δ-valerolactams as Effective Twisted Amide Precursors for Cross-Coupling Reactions
Bisz, Elwira,Chen, Hao,Dziuk, B?a?ej,Ejsmont, Krzysztof,Lalancette, Roger,Pyle, Daniel J.,Rahman, Md. Mahbubur,Szostak, Michal,Szostak, Roman,Wang, Qi
, p. 10455 - 10466 (2021/07/31)
The development of efficient methods for facilitating N-C(O) bond activation in amides is an important objective in organic synthesis that permits the manipulation of the traditionally unreactive amide bonds. Herein, we report a comparative evaluation of a series of cyclic amides as activating groups in amide N-C(O) bond cross-coupling. Evaluation of N-acyl-imides, N-acyl-lactams, and N-acyl-oxazolidinones bearing five- and six-membered rings using Pd(II)-NHC and Pd-phosphine systems reveals the relative reactivity order of N-activating groups in Suzuki-Miyaura cross-coupling. The reactivity of activated phenolic esters and thioesters is evaluated for comparison in O-C(O) and S-C(O) cross-coupling under the same reaction conditions. Most notably, the study reveals N-acyl-δ-valerolactams as a highly effective class of mono-N-acyl-activated amide precursors in cross-coupling. The X-ray structure of the model N-acyl-δ-valerolactam is characterized by an additive Winkler-Dunitz distortion parameter ?(τ+χN) of 54.0°, placing this amide in a medium distortion range of twisted amides. Computational studies provide insight into the structural and energetic parameters of the amide bond, including amidic resonance, N/O-protonation aptitude, and the rotational barrier around the N-C(O) axis. This class of N-acyl-lactams will be a valuable addition to the growing portfolio of amide electrophiles for cross-coupling reactions by acyl-metal intermediates.
Pd/C in Propylene Carbonate: A Sustainable Catalyst–Solvent System for the Carbonylative Suzuki–Miyaura Cross-Coupling Using N-Formylsaccharin as a CO Surrogate
Gautam, Prashant,Gupta, Rashi,Bhanage, Bhalchandra M.
, p. 3431 - 3437 (2017/07/04)
This work documents the first Pd/C-catalyzed carbonylative Suzuki–Miyaura cross-coupling of aryl iodides with N-formylsaccharin as a CO surrogate. In contrast to previous reaction protocols, which make use of toxic and hazardous solvents, the reaction could be advantageously performed in propylene carbonate as an environmentally benign and sustainable polar aprotic solvent. A range of biaryl ketones, including (4-methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone, an antineoplastic belonging to the phenstatin family, could be synthesized under cocatalyst-free, additive-free and ligand-free conditions. The Pd/C could be recycled up to five times under CO surrogacy with only a marginal decrease in catalytic activity. The reaction could also be scaled up to gram-scale syntheses.
Palladium-catalyzed acylative cross-coupling of amides with diarylborinic acids and sodium tetraarylborates
Li, Xijing,Zou, Gang
, p. 136 - 145 (2015/07/27)
Abstract A general and efficient acylative Suzuki coupling of active amides with diarylborinic acids has been achieved by using 1 mol% Pd(PCy3)2Cl2/0.6 mol% PCy3 as catalyst system taking advantage of modifiable reactivities of acyl-nitrogen bonds of amides. Both electronic and steric influences from either aryl or acyl counterparts on the coupling proved to be negligible or small. A variety of aryl ketones including sterically hindered ones could be synthesized by the coupling of diarylborinic acids in good to excellent yields. Sodium tetraarylborates could also be used as high atom-economy aryl source in the palladium-catalyzed cross-coupling with active amides.
